Legacy switching systems required an operator to manually connect calls between an ingress port and an egress port. In general terms, an “ingress port” refers to an input, and an “egress port” refers to an output. Since human interaction is often inefficient and subject to errors, the next generation switching systems were designed for use without the use of operators.
FIG. 1 illustrates a simplified block diagram of a conventional multi-stage cross connect switching system. The multi-stage cross connect switching system can be used to reduce the number of basic elements for a given n×m ports system. In this cross connect switching system, n and m each represents the number of ingress and egress ports, respectively. The n and m values can range from, for example, 10 to 100,000. The capacity of a cross connect system is generally referred to as n×m ports.
This system consists of an Ingress-Switching Stage 22, Core-Switching Stage(s) 24, an Egress-Switching Stage 26, the Inter-Stage Connections 32a, 32b, and the ingress 6 and egress ports 8 for connection to equipments outside the system. The ingress ports are designated as Ig1, Ig2, Igi, . . . . Ign, and the egress ports are designated as Eg1, Eg2, Egi, . . . Egm. Each ingress 6 and egress 8 port consists of a pair of physical wire (i.e., 2 leads). The ingress ports 6 can also be connected to a Main Distribution Frame (“MDF”) (not shown) in a central office. The egress ports 8, likewise, can be connected to another equipment, which may be another MDF.
This multi-stage switching system is used to reduce the number of cross points, but the disadvantage is that there may be a loss of system performance. Also illustrated are the connections within each switching stage. It can be appreciated that conventional interconnect switching systems can be quite complex, prone to errors during installations and maintenance, leading to potential reliability and system performance problems.
A fundamental design characteristic is the interconnection of the leads with each other. The interconnections can take place at different levels including: (1) device level—interconnecting basic elements to form a packaged device; (2) board level—interconnecting devices to form a circuit board; (3) shelf level—interconnecting boards to form a sub-system or system; (4) rack level—interconnecting shelves to form a sub-system or system; and (5) inter-rack level—interconnecting racks to form a sub-system or system. In the U.S. patent application Ser. No. 10/126,281, which contents are hereby incorporated by reference and commonly owned by the same assignee, the challenges associated with designing high density metallic cross connect switching systems were described in great detail.
FIG. 2 illustrates a rear view of a rack with shelves mounted therein. As illustrated, the rack 50 includes multiple shelves 52, 54, 56, which themselves include vertical cards 60 and horizontal cards 62. Each vertical 60 and horizontal 62 card includes a connector 64 for interconnecting to other cards or equipment. These components and their functionality are described in greater detail in the co-pending U.S. patent application Ser. No. 10/126,281.
FIG. 3 illustrates a rear view of the connections made inter-shelf and inter-rack for the high density metallic cross connect system. In greater detail, the inter-shelf connections 80 and inter-rack connections 82 can be implemented with the twisted cable pairs 92. Also, the twisted cable pairs 92 can be used for ingress connections 70 and egress connections 72. The inter-shelf connections 80 and inter-rack connections 82 can be implemented between two horizontal cards or between vertical and horizontal cards. The twisted cable pairs 92 have physical connectors attached at both ends of the cables. The cable length can vary and depends on the capacity of a particular system configuration.
As can be appreciated, an enormous amount of cables and space are needed to interconnect the various components of the high density metallic cross connect system. In addition, the following issues must be addressed during installation and maintenance: (1) space constraints can limit the accessibility and visibility of cables and the components, thereby resulting in errors during installation; (2) verification of properly connected cables is needed; (3) ability to add and/or removal cables and components; and (4) ability to detect faults. In particular, a cable installer must connect the cables without any errors. For example, the installer must connect one end of the cable to a particular connector within a particular slot within a particular shelf on the correct rack. Likewise, the installer must correctly connect the other end of the cable in the correct connector within a particular slot within a particular shelf on the correct rack. Obviously, this manual procedure is prone to many errors. Accordingly, the present invention is intended to provide a means for connecting the cables to cards while reducing such errors.
As detailed above, the conventional interconnect methods and techniques are inadequate and unworkable because of their physical interconnection tasks are enormous and extremely complex. One of the key challenges is to design and develop the physical interconnections for the overall system in an efficient and simplified manner. Accordingly, there is a need for a “smart cable system” to interconnect shelves and racks in an efficient and reliable manner to construct high density metallic cross connect switching systems.